Draining the font swamp

[Matthew Garrett]

On Mon, May 21, 2007 at 10:52:46AM -0400, Phillip Susi wrote:

> 3)  Performance suffers.  The X server is in the best position to render 
> fonts using any hardware acceleration provided by the video card, and 
> allows for those fonts to be shared by all applications, reducing 
> duplication and waste.  Also for remote X sessions, you want the fonts 
> rendered on the server so much less data needs exchanged between the 
> client and server.

Measurements have shown that over pretty much any sort of common 
network, latency is more of a problem than bandwidth. Server-side fonts 
require multiple round-trips between the server and the client for 
rendering, whereas client-side fonts only require the initial display. 
Performance-wise, we have the XRender extension for precisely this sort 
of situation.

> Other than the fact that the client side implementations have advanced 
> beyond the X server ones in recent times, is there any advantage to 
> client side font rendering over server side?  If not, then we should 
> push to bring the client side advancements back into the server where 
> font rendering belongs.

Font choice and layout is hard, and doesn't become any easier just 
because you've moved that code to a binary that runs as root. Nobody is 
going to argue in favour of putting a layout engine like Pango in the X 
server, and most of the rest of the stack is similarly well outside the 
scope of the X server. The client-side font revolution happened 5 years 
ago, and we've ended up with massively improved font support as a 
result.

-- 
Matthew Garrett | mjg59 at srcf.ucam.org